1. Field of the Invention
The present invention relates to a floor conveyor that conveys a carriage with a conveyed article or material mounted on it, and more specifically to a floor conveyor for use, in an automobile manufacturing line or the like, to convey on a floor conveyed material or articles such as car assembly parts to various processes such as a welding process, assembling process, etc.
2. Description of the Related Art
Various different floor conveyor systems have been used in the past for conveying carriages with a conveyed materials. One typical type of conveyor is a floor chain conveyor that conveys a carriage by driving circulating conveyor chains with multiple conveyor carriers linked to the chains. Another is a mobile carriage that travels on wheels on the work floor by means of a power feeding driving means.
The conventional floor conveyor systems mentioned above involve the several problems. In the conventional floor chain conveyor, a drive means such as a chain feeder or the like is used which makes the system construction large and complicated. Moreover, the sliding of the conveyor chains on a conveyor guide rail is apt to create noise. Further, since the center of gravity of the conveyor and its load in combination is relatively high when heavy conveyed materials or objects are loaded on the upper part of the conveyor, the floor chain conveyor tends to exhibit roll vibration, that is the conveyor and its load may oscillate rotationally right and left about an axis extending in the direction of conveyor movement. Further, maintenance work such as the periodic oiling of the conveyor chains, the individual removal of conveyor carriers, etc., is a nuisance, which presents another problem to be solved.
Also, in the conventional floor mobile carriage, since a collector terminal is used to feed power to the drive motor that drives the wheels of the carriage, sliding abrasion is created on the collector terminal during conveyance, and the sliding stirs up dust which adheres to the conveyed material to create spots thereon which require further processing. This is a serious disadvantage. Moreover, since the feeder line has to be laid through the total length of the rail, the laying cost is burdensome and is a problem to be solved.
The present invention addresses the aforementioned disadvantages of conventional conveyor systems, and it is an object of the invention to provide a friction drive system floor conveyor that securely conveys heavy conveyed materials with low noise and without rolling, in a stable stale, simplifies system construction, and facilitates maintenance work.
To achieve the foregoing object, the friction drive system floor conveyor in accordance with one aspect of the invention is provided with a tubular guide rail laid along a conveyor line and a tubular support rail laid directly above the tubular guide rail in parallel therewith. Multiple inverted J-shaped carriers are provided, having support rollers freely pivoted to their upper ends. These support rollers ride on the top side of the tubular support rail in the longitudinal direction thereof. A pair of guide rollers is also provided. The guide rollers are pivoted to the lower end of the inverted J-shaped carrier, and embrace both the sides of the tubular guide rail. Driven bars mutually link the bases of the inverted J-shaped carriers, and are disposed between the tubular guide rail and the tubular support rail. A carriage support bracket is installed upright to the driven bar to support a carriage above the floor of the conveyor line. A friction drive means disposed along the conveyor line, engages the driven bar on both sides thereof, to move the conveyor in the conveying direction.
In one preferred form of the friction drive system floor conveyor, the friction drive means comprises a friction roller that engages one side of the driven bar to convey the driven bar in the conveyance direction, and a passive roller that comes in contact with the other side of the driven bar to guide the driven bar in the conveyance direction.
Generally the entire conveyor is exposed on the floor, in view of the need for maintenance work on the conveyor. However, from the consideration of the working environment along the conveyor line, it is also possible to adopt a double flooring structure and construct the friction drive system floor conveyor in a form such that only the upper parts of the carriage support brackets are exposed above the upper floor.
Further, in the friction drive system floor conveyor of the invention, the carriage supported on the upper end of the carriage support bracket may take any form, as long as it is able to carry a conveyed material or article. Thus, the carriage may be in the form of a stand, plate, frame, basket, tray, etc. depending on the form and structure, etc. of the conveyed material or article.
Also, the tubular guide rail and the tubular support rail may be any tubular rails, as long as the material thereof has the characteristics of light weight and strength, and this kind of rail material will achieve the most suitable layout along the conveyor line.
Further, with regard to the configuration of the driven bar and the friction drive means, as long as the friction drive means can securely engage the driven bar and move the driven bar in the conveying direction, the mutually engaging surfaces can be concave and convex respectively, or flat. For efficient power transmission to the driven bars, it is preferable that the side faces of the driven bar be flat and that the faces of the friction drive means be in the form of circular cylinders, so that line contact is achieved between the friction drive means and the driven bars.
Further, with regard to the layout of the friction drive means in the friction drive system floor conveyor of the invention, from the consideration of simplifying the system construction, the friction drive means are not required to be laid out in one-to-one correspondence with the driven bars, and it is especially preferable that the friction drive means be concentrated where the greatest conveyance power is needed, such as a carrying-in area, curved corner, and carrying-out area, etc. in the conveyor line.
The friction drive system floor conveyor of the invention thus constructed exhibits the following functions.
The friction drive system floor conveyor includes the driven bar and the friction drive means, and the friction drive means engages both sides of the driven bar to move the driven bar in the conveying direction. This generates a conveying force by the friction exerted between the drive means and the bar. Thus, the friction drive system floor conveyor exhibits a so-called friction drive function.
Further, since the friction drive system floor conveyor is provided with a large number of inverted J-shaped carriers with free rollers pivoted on the upper ends uhereof and a tubular support rail, the free rollers pivoted to the inverted J-shaped carriers roll smoothly on, and in line contact with, the tubular support rail in the longitudinal direction thereof. This suppresses contact noises which are otherwise likely to be generated at the location at which the conveyor is supported. Thus, the friction drive system floor conveyor also exhibits a so-called contact noise suppressing function.
Further, since the tubular guide rail and the pairs of guide rollers are disposed under the position at which the driven bar is held, even if a rolling moment is exerted to the right or left by a conveyed material having a high center of gravity or by an especially heavy conveyed material, the tubular guide rail and the guide rollers securely maintain the inverted J-shaped carrier in an upright attitude, preventing right or left rolling motion of the carriage. Thus, the friction drive system floor conveyor also exhibits a so-called roll prevention function.
Since the driven bars mutually link the bases of the inverted J-shaped carriers, even though the driven bar is straight, it can smoothly follow the locus of the arc at the curved corners of a conveyor line, both ends of the driven bar being suspended, and the bar forming a chord. Thus, the friction drive system floor conveyor exhibits a so-called arc line following function.
Finally, since the friction roller engages one side of the driven bar to drive the bar in the conveying direction, and the passive roller engages the other side of the driven bar to guide it, and the two rollers embrace the bar on both sides, the conveying force is transmitted smoothly to the bar by the friction roller without loss. Thus, the friction drive system floor conveyor also displays a so-called conveyance force loss prevention function.